1/**
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.internal.util;
18
19import android.os.Message;
20
21/**
22 * {@hide}
23 *
24 * The interface for implementing states in a {@link StateMachine}
25 */
26public interface IState {
27
28    /**
29     * Returned by processMessage to indicate the the message was processed.
30     */
31    static final boolean HANDLED = true;
32
33    /**
34     * Returned by processMessage to indicate the the message was NOT processed.
35     */
36    static final boolean NOT_HANDLED = false;
37
38    /**
39     * Called when a state is entered.
40     */
41    void enter();
42
43    /**
44     * Called when a state is exited.
45     */
46    void exit();
47
48    /**
49     * Called when a message is to be processed by the
50     * state machine.
51     *
52     * This routine is never reentered thus no synchronization
53     * is needed as only one processMessage method will ever be
54     * executing within a state machine at any given time. This
55     * does mean that processing by this routine must be completed
56     * as expeditiously as possible as no subsequent messages will
57     * be processed until this routine returns.
58     *
59     * @param msg to process
60     * @return HANDLED if processing has completed and NOT_HANDLED
61     *         if the message wasn't processed.
62     */
63    boolean processMessage(Message msg);
64
65    /**
66     * Name of State for debugging purposes.
67     *
68     * @return name of state.
69     */
70    String getName();
71}
72